Glycolurils are heterocyclic compounds having four urea nitrogen atoms in the ring structure thereof, and are used in various applications and productions of novel functional compounds, utilizing the reactivity of the urea nitrogen.
It is known, for example, that the glycoluril is reacted with an aldehyde such as dimethoxyethanal to produce an aminoplastic resin, and the obtained resin is used as a cross-linking agent for cellulose (see Patent Document 1).
It is also known that an emulsion comprising a copolymer of vinyl acetate, ethylene, and a self-crosslinkable monomer, and a tetramethylol glycoluril is used as a binder for a non-woven fabric (see Patent Document 2). It is further known to use the tetramethylol glycoluril as a cross-linking agent for fixing a polyhexamethylene biguanide compound, which is a water-soluble polymer antimicrobial agent to a fiber (see Patent Document 3).
Meanwhile, compounds having plural allyl groups rich in reactivity in the molecule, such as triallylisocyanurates, are well-known as a cross-linking agent for synthetic resins and synthetic rubber. Similarly, tetraallyl-glycolurils having four allyl groups in the molecule, which function as a cross-linking agent for synthetic resins and synthetic rubber, are also known (see Patent Document 4).
Also, compounds having plural thiol groups in the molecule are well-known, for example, as a curing agent for an epoxy resin. For example, an epoxy resin composition comprising a polythiol compound as a curing agent and a reaction product of an amine with an epoxy compound as a curing accelerator is proposed. It is said that the epoxy resin composition has a long pot life and is quickly cured at a comparatively low temperature (see Patent Document 5).
An epoxy resin composition comprising, as a curing accelerator, a reaction product of an isocyanate compound having one or more isocyanate groups in the molecule with a compound having at least one primary and/or secondary amino group in the molecule is also proposed. It is said that the epoxy resin composition also has a long pot life and is superior in curability (see Patent Document 6).
Tris(3-mercaptopropyl)isocyanurate, which is also called “trithiol isocyanurate,” has no ester group in the molecule. Thus, the use thereof as a curing agent capable of providing a cured product of epoxy resin superior in water resistance is proposed (see Patent Document 7).
A compound in which a hydrogen atom on at least one nitrogen atom of the glycoluril is replaced by a mercaptoalkyl group is useful, for example, as an intermediate for synthesizing a novel sulfur-containing compound or the like, and as a modifier such as a diluent for an epoxy resin or a plasticity-imparting agent, and it is expected to be useful as a curing agent for an epoxy resin. The compound in which a hydrogen atom on at least one nitrogen atom of the glycoluril is replaced by a mercaptoalkyl group, however, is still remains unknown.
Meanwhile, one of the important uses of the epoxy resin composition is use in a multilayer printed circuit board. Recently, as a method for producing a multilayer printed circuit board, a production technology of a build-up method in which a conductor layer on an inner layer circuit board and an organic insulating layer are alternatively stacked is receiving attention. For example, there is proposed a method for producing a multilayer printed circuit board comprising the steps of: coating a circuit-formed inner layer circuit board with an epoxy resin composition, curing it by heating, forming a roughened surface using a roughening agent, and forming a conductor layer on the roughened surface by plating (see Patent Documents 8 and 9).
A method for producing a multilayer printed circuit board is also disclosed which comprises the steps of: coating an inner layer circuit board with a primer adhesive, temporarily drying it, pasting it to a film-like additive adhesive, heating and curing it, roughening it with an alkaline oxidant, and forming a conductor layer by plating (see Patent Document 10).
An amine curing agent such as a dicyandiamide or imidazole compound is typically used as a curing agent in the epoxy resin composition used in the use described above. However, with the increase of a packaging density which has been recently advanced, a curing system superior in heat resistance to that of conventional system has also been desired in the interlayer insulating material used in the build-up method, similar to laminates.
Then, an epoxy resin composition for an interlayer insulating material is proposed which uses a phenol curing agent having a triazine structure and has both high heat resistance and surface-roughened property by an oxidant (see Patent Document 11).
The epoxy resin composition, however, contains a roughening component such as a rubber component as a requisite component, and thus the heat resistance and electric insulation thereof may sometimes be an issue in a field requiring more fine-patterning or thinner thickness of the insulating layer. When a phosphorus atom-containing epoxy resin, which is receiving attention as a flame-retardant epoxy resin from recent environmental issues, is used instead of a bromine-containing epoxy resin, a satisfactorily roughened surface cannot be obtained from an existing resin composition, and a conductor layer which is subsequently obtained by plating problematically has a weak peel strength.